From 44bf251a42ac6dd416b0454d168d426dd55e714b Mon Sep 17 00:00:00 2001 From: =?utf8?q?Martin=20Storsj=C3=B6?= Date: Tue, 18 May 2010 19:48:25 +0000 Subject: [PATCH] Use a heuristic for describing the RTP packets using sample data Originally committed as revision 23165 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavformat/movenc.h | 16 ++++ libavformat/movenchint.c | 216 ++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 230 insertions(+), 2 deletions(-) diff --git a/libavformat/movenc.h b/libavformat/movenc.h index 3d8f4ba49..182c5edc8 100644 --- a/libavformat/movenc.h +++ b/libavformat/movenc.h @@ -51,6 +51,20 @@ typedef struct MOVIentry { uint32_t flags; } MOVIentry; +typedef struct HintSample { + uint8_t *data; + int size; + int sample_number; + int offset; + int own_data; +} HintSample; + +typedef struct { + int size; + int len; + HintSample *samples; +} HintSampleQueue; + typedef struct MOVIndex { int mode; int entry; @@ -82,6 +96,8 @@ typedef struct MOVIndex { uint32_t prev_rtp_ts; int64_t cur_rtp_ts_unwrapped; uint32_t max_packet_size; + + HintSampleQueue sample_queue; } MOVTrack; typedef struct MOVMuxContext { diff --git a/libavformat/movenchint.c b/libavformat/movenchint.c index e830b741a..d90ac6791 100644 --- a/libavformat/movenchint.c +++ b/libavformat/movenchint.c @@ -98,6 +98,188 @@ fail: return ret; } +/** + * Remove the first sample from the sample queue. + */ +static void sample_queue_pop(HintSampleQueue *queue) +{ + if (queue->len <= 0) + return; + if (queue->samples[0].own_data) + av_free(queue->samples[0].data); + queue->len--; + memmove(queue->samples, queue->samples + 1, sizeof(HintSample)*queue->len); +} + +/** + * Empty the sample queue, releasing all memory. + */ +static void sample_queue_free(HintSampleQueue *queue) +{ + int i; + for (i = 0; i < queue->len; i++) + if (queue->samples[i].own_data) + av_free(queue->samples[i].data); + av_freep(&queue->samples); + queue->len = 0; + queue->size = 0; +} + +/** + * Add a reference to the sample data to the sample queue. The data is + * not copied. sample_queue_retain should be called before pkt->data + * is reused/freed. + */ +static void sample_queue_push(HintSampleQueue *queue, AVPacket *pkt, int sample) +{ + /* No need to keep track of smaller samples, since describing them + * with immediates is more efficient. */ + if (pkt->size <= 14) + return; + if (!queue->samples || queue->len >= queue->size) { + HintSample* samples; + queue->size += 10; + samples = av_realloc(queue->samples, sizeof(HintSample)*queue->size); + if (!samples) + return; + queue->samples = samples; + } + queue->samples[queue->len].data = pkt->data; + queue->samples[queue->len].size = pkt->size; + queue->samples[queue->len].sample_number = sample; + queue->samples[queue->len].offset = 0; + queue->samples[queue->len].own_data = 0; + queue->len++; +} + +/** + * Make local copies of all referenced sample data in the queue. + */ +static void sample_queue_retain(HintSampleQueue *queue) +{ + int i; + for (i = 0; i < queue->len; ) { + HintSample *sample = &queue->samples[i]; + if (!sample->own_data) { + uint8_t* ptr = av_malloc(sample->size); + if (!ptr) { + /* Unable to allocate memory for this one, remove it */ + memmove(queue->samples + i, queue->samples + i + 1, + sizeof(HintSample)*(queue->len - i - 1)); + queue->len--; + continue; + } + memcpy(ptr, sample->data, sample->size); + sample->data = ptr; + sample->own_data = 1; + } + i++; + } +} + +/** + * Find matches of needle[n_pos ->] within haystack. If a sufficiently + * large match is found, matching bytes before n_pos are included + * in the match, too (within the limits of the arrays). + * + * @param haystack buffer that may contain parts of needle + * @param h_len length of the haystack buffer + * @param needle buffer containing source data that have been used to + * construct haystack + * @param n_pos start position in needle used for looking for matches + * @param n_len length of the needle buffer + * @param match_h_offset_ptr offset of the first matching byte within haystack + * @param match_n_offset_ptr offset of the first matching byte within needle + * @param match_len_ptr length of the matched segment + * @return 0 if a match was found, < 0 if no match was found + */ +static int match_segments(const uint8_t *haystack, int h_len, + const uint8_t *needle, int n_pos, int n_len, + int *match_h_offset_ptr, int *match_n_offset_ptr, + int *match_len_ptr) +{ + int h_pos; + for (h_pos = 0; h_pos < h_len; h_pos++) { + int match_len = 0; + int match_h_pos, match_n_pos; + + /* Check how many bytes match at needle[n_pos] and haystack[h_pos] */ + while (h_pos + match_len < h_len && n_pos + match_len < n_len && + needle[n_pos + match_len] == haystack[h_pos + match_len]) + match_len++; + if (match_len <= 8) + continue; + + /* If a sufficiently large match was found, try to expand + * the matched segment backwards. */ + match_h_pos = h_pos; + match_n_pos = n_pos; + while (match_n_pos > 0 && match_h_pos > 0 && + needle[match_n_pos - 1] == haystack[match_h_pos - 1]) { + match_n_pos--; + match_h_pos--; + match_len++; + } + if (match_len <= 14) + continue; + *match_h_offset_ptr = match_h_pos; + *match_n_offset_ptr = match_n_pos; + *match_len_ptr = match_len; + return 0; + } + return -1; +} + +/** + * Look for segments in samples in the sample queue matching the data + * in ptr. Samples not matching are removed from the queue. If a match + * is found, the next time it will look for matches starting from the + * end of the previous matched segment. + * + * @param data data to find matches for in the sample queue + * @param len length of the data buffer + * @param queue samples used for looking for matching segments + * @param pos the offset in data of the matched segment + * @param match_sample the number of the sample that contained the match + * @param match_offset the offset of the matched segment within the sample + * @param match_len the length of the matched segment + * @return 0 if a match was found, < 0 if no match was found + */ +static int find_sample_match(const uint8_t *data, int len, + HintSampleQueue *queue, int *pos, + int *match_sample, int *match_offset, + int *match_len) +{ + while (queue->len > 0) { + HintSample *sample = &queue->samples[0]; + /* If looking for matches in a new sample, skip the first 5 bytes, + * since they often may be modified/removed in the output packet. */ + if (sample->offset == 0 && sample->size > 5) + sample->offset = 5; + + if (match_segments(data, len, sample->data, sample->offset, + sample->size, pos, match_offset, match_len) == 0) { + *match_sample = sample->sample_number; + /* Next time, look for matches at this offset, with a little + * margin to this match. */ + sample->offset = *match_offset + *match_len + 5; + if (sample->offset + 10 >= sample->size) + sample_queue_pop(queue); /* Not enough useful data left */ + return 0; + } + + if (sample->offset < 10 && sample->size > 20) { + /* No match found from the start of the sample, + * try from the middle of the sample instead. */ + sample->offset = sample->size/2; + } else { + /* No match for this sample, remove it */ + sample_queue_pop(queue); + } + } + return -1; +} + static void output_immediate(const uint8_t *data, int size, ByteIOContext *out, int *entries) { @@ -118,10 +300,36 @@ static void output_immediate(const uint8_t *data, int size, } } +static void output_match(ByteIOContext *out, int match_sample, + int match_offset, int match_len, int *entries) +{ + put_byte(out, 2); /* sample constructor */ + put_byte(out, 0); /* track reference */ + put_be16(out, match_len); + put_be32(out, match_sample); + put_be32(out, match_offset); + put_be16(out, 1); /* bytes per block */ + put_be16(out, 1); /* samples per block */ + (*entries)++; +} + static void describe_payload(const uint8_t *data, int size, - ByteIOContext *out, int *entries) + ByteIOContext *out, int *entries, + HintSampleQueue *queue) { /* Describe the payload using different constructors */ + while (size > 0) { + int match_sample, match_offset, match_len, pos; + if (find_sample_match(data, size, queue, &pos, &match_sample, + &match_offset, &match_len) < 0) + break; + output_immediate(data, pos, out, entries); + data += pos; + size -= pos; + output_match(out, match_sample, match_offset, match_len, entries); + data += match_len; + size -= match_len; + } output_immediate(data, size, out, entries); } @@ -195,7 +403,7 @@ static int write_hint_packets(ByteIOContext *out, const uint8_t *data, entries = 0; /* Write one or more constructors describing the payload data */ - describe_payload(data, packet_len, out, &entries); + describe_payload(data, packet_len, out, &entries, &trk->sample_queue); data += packet_len; size -= packet_len; @@ -230,6 +438,8 @@ int ff_mov_add_hinted_packet(AVFormatContext *s, AVPacket *pkt, if (!rtp_ctx->pb) return AVERROR(ENOMEM); + sample_queue_push(&trk->sample_queue, pkt, sample); + /* Feed the packet to the RTP muxer */ local_pkt = *pkt; local_pkt.stream_index = 0; @@ -269,6 +479,7 @@ int ff_mov_add_hinted_packet(AVFormatContext *s, AVPacket *pkt, ff_mov_write_packet(s, &hint_pkt); done: av_free(buf); + sample_queue_retain(&trk->sample_queue); return ret; } @@ -277,6 +488,7 @@ void ff_mov_close_hinting(MOVTrack *track) { uint8_t *ptr; av_freep(&track->enc); + sample_queue_free(&track->sample_queue); if (!rtp_ctx) return; if (rtp_ctx->pb) { -- 2.11.0